《Java2图形设计卷II：Swing》配套光盘源码

				import javax.swing.*;
				import java.awt.*;
				import java.awt.event.*;
				
				public class TestApplet extends JApplet {
					public void init() {
						Container contentPane = getContentPane();
						final JPanel panel = new JPanel();
						JButton button = new JButton("repaint");
				
						panel.setBackground(Color.blue);
						panel.setPreferredSize(new Dimension(100,100));
				
						contentPane.setLayout(new FlowLayout());
						contentPane.add(button);
						contentPane.add(panel);
				
						button.addActionListener(new ActionListener() {
							public void actionPerformed(ActionEvent e) {
								Color c = panel.getBackground();
								Dimension sz = panel.getSize();
				
								panel.setBackground(
									c == Color.blue ? Color.red : Color.blue);
				
								panel.paintImmediately(
												0,0,sz.width,sz.height);
				
								// for illustrative purposes only
								try {
									Thread.currentThread().sleep(5000);
								}
								catch(InterruptedException ex) {
									ex.printStackTrace();
								}
							}
						});
					}
				}